Re: Scanner/Digitizer skip function/probe details?

Dave,

We were talking about this back in Nov. Is this what you mean?

>Jon,
>
>How small? Which encoders/parts? the HP's I have are BIG. I was
>thinking "Last Word" dial indicator, size wise, for Sherline-sized
>hardware.
>
>I wonder if a "photo-interrupter" could be used? A little deflection
>would move the vain/tip out of the light path. Wouldn't give mills of
>deflection, but could still be useful.
>
>Alan

Alan KM6VV

dave engvall wrote:

>
> Alan Marconett KM6VV wrote:
>
> > Dave,
> >
> > Yes, I was thinking about that, an encoder wheel on a dial indicator, or
> > a photo-interrupter actuated by a vane (needle) moved by a contact. Or
> > strain guages. What I haven't figured out is how to get 3D. 2D from
> > the strain guages, but 3rd is tough. Maybe if object was on a rotary
> > table (C axis), then we could approach in more limited directions? Any
> > ideas?
> >
> > I'm thinking each G61 move "collects" a data point, and they are saved
> > in .DLG format (Digital Line Drawing), .DEM (Digital Elevation Map),
> > .DXF or Gcode.
> >
> > Alan KM6VV
> >
>
> > snip all my old comments and Ballendo's.
> let me try this in another format: opti pair (emitter, phototransistor) at angle i.e one of the reflector types....looking at the
> needle so when one gets deflection of a half thou or so you change states on the transistor.
>
> Maybe something primitive in terms of a program: capable of doing an x,y grid at the desired granularity. Now you need something to
> advance the Z axis until you get a state change....and read Z axis....this is not going to be fast. :-( Post process for to
> compensate for slope, i.e. the unless slope is zero the point of contact with a spherical probe end will not be the real point of
> contact( but the solution is straight trig). After compensation (correction) this gives a point map in x, y and z which will have to
> be processed again to give you g-code to duplicate the surface. Naturally if you have overhangs this won't work and vertical walls
> will probably need another routine which slides along the wall taking points. All in all this is not a simple process.
> Hope someone has a better idea.
>
> Dave
>
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